11Alive's Tampa sister station WTSP says they do not typically identify suspects this young, but chose to identify Roman and Shaw for the following reasons:

THE SERIOUS NATURE OF THE CHARGES. The two suspects are charged with Felony Aggravated Stalking, a serious crime that suggests a pattern of deliberate and premeditated criminal behavior.

THE CRIME INVOLVES DEATH. Investigators allege that the pattern of abusive and threatening behavior likely contributed to Rebecca's suicide.

Polk Sheriff Grady Judd says Shaw and Roman were the two girls who primarily bullied Rebecca.

Judd says a feud erupted after Shaw began dating Rebecca's ex-boyfriend. Witnesses told investigators Shaw had several arguments with Rebecca on Facebook, as well as verbal confrontations at school over. The witnesses said Rebecca would not engage in the confrontations and instead would walk away. Shaw also reportedly bullied anyone who was friends with Rebecca.

Shaw allegedly sent messages to Rebecca, calling her ugly, telling her to drink bleach and die, and telling Rebecca that she [Rebecca] should kill herself. Shaw tried to instigate physical fights with Rebecca on more than one occasion.

Shaw also instigated fighting between Katelyn Roman and Rebecca. Sheriff Judd says Roman was once best friends with Rebecca, until Shaw convinced Roman to turn on her.

Roman was suspended for one fight that occurred in February 2013, during which Shaw encouraged Roman to "beat up" Rebecca. Rebecca did not fight back.

When interviewed recently by detectives, Roman admitted that she "bullied" Rebecca, and that she was sorry for doing it.

Judd says the tipping point in their investigation that led to the arrests was when Shaw showed a lack of remorse for Rebecca's death, posting Saturday morning on Facebook, "Yes ik [I know] I bullied REBECCA nd she killed her self but IDGAF [I don't give a f***]"

Shaw told deputies that her Facebook account was hacked and she did not write that post.

Both girls were booked into juvenile detention on Monday night. They have since been released into their parents' custody and are on home detention. Judd says the girls had previous problems at school, but had no previous arrest history.

Judd says the investigation continues into other teens and pre-teens who may have stalked and bullied Rebecca.

"They would tell her she's ugly, stupid, nobody liked her go kill herself," Rebecca's mother, Tricia Norman, told 10 News last month. She says the constant bullying drove her daughter to kill herself, and that the school district did not do enough to protect her.

Sheriff Judd said in an earlier press conference in November, Rebecca ran away and in December she was hospitalized for three days after cutting herself. There were school fights and at that point the school stepped in to separate the girls' schedules and, later, Rebecca even changed schools.

But the bullying continued online, on sites such as Ask.fm, Kik, Instagram and Voxer.

Sheriff Judd said the "red flags" for possible suicide were there.

"We found on Rebecca's Internet search engines, or search questions: What is overweight for a 13-year-old girl? How to get blades out of razors? How many Advil do you need to take to die?"

Judd said on that tragic September morning, Rebecca texted a boy she had met online in North Carolina from the cement tower, saying she was jumping and she couldn't take it anymore.